In the medical arts, catheters are frequently used to diagnose and treat various disorders in a patient, such as clogged or blocked blood vessels. A catheter is introduced into a blood vessel of a patient by, for example, making an incision in the patient over the blood vessel and inserting the catheter into the blood vessel of the patient. A catheter operator such as a physician then maneuvers the catheter through the blood vessels of the patient until the catheter is properly situated to diagnose or treat the disorder. Similar techniques are used to insert catheters into other types of lumens within a patient.
In maneuvering the catheter through the blood vessels or other lumens within the patient, there is a recurrent need to know the location of the catheter within the body space of the patient. Conventional imaging systems create an image of the blood vessel or other lumen which make the lumen appear as a straight tube, and provide no concept of 3-dimensional (“3-D”) spatial relationships. In the patient, however, the lumens curve about, and contain branches that branch off at various angles from the lumen. If the position in three dimensions of the imaging head on the catheter can be determined, then through use of three-dimensional imaging software, the true positions and locations of the curves, twists, and turns, as well as the locations of the branch points, of the lumens can be determined. Knowing the true positions allows a more accurate map of the patient to be created, which yields more effective diagnosis and treatment of the patient. For example, gathering accurate 3-D position data allows for an accurate blood flow map and consequent blood flow monitoring and modeling.
Traditionally, X-ray technology has been used to provide a global roadmap of X-ray visible devices, showing their position within the patient. However, an X-ray image, being a two-dimensional projection, can only provide partial information on the 3-D shape of the catheter path. Furthermore, prolonged exposure to X-rays may be harmful to the patient, and it is therefore desirable to avoid such exposures. Thus there is a need for a tracking system which can easily determine the location of a catheter within a patient, without exposing the patient to harmful side effects, and which can be used with a wide variety of catheters or other imaging medical devices.
To overcome the problems inherent with X-ray tracking of catheters, various technologies have arisen which attempt to gather positional information about the location of a catheter within the patient, without the harmful side-effects of X-ray technology. Among such technologies are tracking systems which gather positional information using electromagnetic, optical, mechanical, acoustic, and/or inertial sensing elements. Many of these technologies require the addition of extra elements to the catheter, to allow it to be tracked within the patient.
Therefore there is a need for an improved method of tracking catheters.